This invention relates generally to post mix dispensing systems, and more particularly to methods and apparatus for mixing together and dispensing two liquids, one of which is charged or carbonated.
Systems of this particular type are typically used to dispense soft drinks, by mixing together a flavored syrup and carbonated water. The systems normally inject both carbonated water, typically under several atmospheres of pressure, and syrup into a mixing chamber, where turbulence of the fluid flow insures thorough mixing. The mixed soft drink is then dispensed through a suitable nozzle. A sharp reduction in the pressure of the carbonated water normally occurs when it is injected into the mixing chamber, thereby causing a portion of the gases dissolved in the water to come out of solution at that time. Unfortunately, the presence of the syrup, which ordinarily has a relatively high viscosity, traps the gases being released to form undesired bubbles or foam.
Some prior systems have been designed to reduce this undesired foaming by delaying the mixing of the carbonated water and syrup until after the two liquids have exited the nozzle. Although these systems have in general produced less foam, they have not proven to be entirely satisfactory. Many of these systems are believed to have been configured such that an insufficient proportion of the gases that have come out of solution escape from the water before it is mixed with the syrup. The syrup therefore traps much of the gas that doesn't escape, to generate an excessive amount of foam. Also, many of these systems are believed to be unduly complex, adding to their expense and making them more difficult to clean.
It should therefore be appreciated that there is still a need for a post mix dispensing method and apparatus in which two liquids, one of which is charged, are thoroughly mixed together and dispensed with even less foam being generated. The present invention fulfills this need.